Lithographic technique for feature cut by line-end shrink

ABSTRACT

A technique for patterning a workpiece such as an integrated circuit workpiece is provided. In an exemplary embodiment, the method includes receiving a dataset specifying a plurality features to be formed on the workpiece. A first patterning of a hard mask of the workpiece is performed based on a first set of features of the plurality of features, and a first spacer material is deposited on a sidewall of the patterned hard mask. A second patterning is performed based on a second set of features, and a second spacer material is deposited on a sidewall of the first spacer material. A third patterning is performed based on a third set of features. A portion of the workpiece is selectively processed using a pattern defined by a remainder of at least one of the patterned hard mask layer, the first spacer material, or the second spacer material.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent ApplicationSer. No. 62/094,759, filed on Dec. 19, 2014, the entire disclosure ofwhich is hereby incorporated herein by reference.

BACKGROUND

The semiconductor integrated circuit (IC) industry has experienced rapidgrowth. In the course of IC evolution, functional density (i.e., thenumber of interconnected devices per chip area) has generally increasedwhile geometry size (i.e., the smallest component (or line) that can becreated using a fabrication process) has decreased. This scaling downprocess generally provides benefits by increasing production efficiencyand lowering associated costs. However, such scaling down has also beenaccompanied by increased complexity in design and manufacturing ofdevices incorporating these ICs, and, for these advances to be realized,similar developments in device fabrication are needed.

As merely one example, advances in lithography have been important toreducing device size. In general, lithography is the formation of apattern on a target. In one type of lithography, referred to asphotolithography, radiation such as ultraviolet light passes through orreflects off a mask before striking a photoresist coating on the target.Photolithography transfers a pattern from the mask onto the photoresist,which is then selectively removed to reveal the pattern. The target thenundergoes processing steps that take advantage of the shape of theremaining photoresist to create features on the target. Another type oflithography, referred to as direct-write lithography, uses a laser, anelectron beam (e-beam), ion beam, or other narrow-focused emission toexpose a resist coating or to pattern a material layer directly. E-beamlithography is one of the most common types of direct-write lithography,and, by directing a collimated stream of electrons to the area to beexposed, can be used to remove, add, or otherwise change a materiallayer with remarkable accuracy.

In order to pursue even smaller critical dimensions (CD) of devicefeatures, multiple lithographic patterning iterations may be performedin order to define a single set of features. However, because of thecomplex interactions between the lithographic iterations, many suchprocesses involve strict design rules specific to the lithographictechniques to be used. Design rules associated with a particularlithographic flow may not be acceptable for all designs. Therefore,while existing lithographic techniques have been generally adequate,they have not proved entirely satisfactory in all respects. Improvedtechniques for multiple patterning may relax existing design rules,overcome existing limitations, and thereby enable even more robustcircuit devices to be manufactured.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure is best understood from the following detaileddescription when read with the accompanying figures. It is emphasizedthat, in accordance with the standard practice in the industry, variousfeatures are not drawn to scale and are used for illustration purposesonly. In fact, the dimensions of the various features may be arbitrarilyincreased or reduced for clarity of discussion.

FIG. 1A is a flow diagram of a first lithographic method for patterninga workpiece according to various aspects of the present disclosure.

FIGS. 1B-1H are perspective views of a portion of a workpiece undergoingthe first lithographic method according to various aspects of thepresent disclosure.

FIG. 1I is a top view of another portion of the workpiece undergoing thefirst lithographic method according to various aspects of the presentdisclosure.

FIG. 2A is a flow diagram of a second lithographic method for patterninga workpiece according to various aspects of the present disclosure.

FIGS. 2B-2H are perspective views of a portion of a workpiece undergoingthe second lithographic method according to various aspects of thepresent disclosure.

FIG. 2I is a top view of another portion of the workpiece undergoing thesecond lithographic method according to various aspects of the presentdisclosure.

FIG. 3 is a flow diagram of a method for patterning a workpieceaccording to various aspects of the present disclosure.

FIG. 4 is a representation of a design database specifying a pattern tobe formed on a workpiece according to various aspects of the presentdisclosure.

FIGS. 5A, 6A, 7A, 8A, 9A, 10A, 11A, 12A, 13A, 14A, 15A, and 16A are topviews of a portion of a workpiece undergoing a patterning methodaccording to various aspects of the present disclosure.

FIGS. 5B, 6B, 7B, 8B, 9B, 10B, 11B, 12B, 13B, 14B, 15B and 16B arecross-sectional views of a portion of a workpiece undergoing apatterning method according to various aspects of the presentdisclosure.

FIG. 17 is a scanning-electron microscope (SEM) image of a workpiecehaving undergone the patterning method according to various aspects ofthe present disclosure.

FIG. 18 is a system diagram of a computing system operable to performthe techniques of the present disclosure.

DETAILED DESCRIPTION

The present disclosure relates generally to IC device manufacturing and,more particularly, to a system and technique for lithographicallypatterning a workpiece to form a set of features.

The following disclosure provides many different embodiments, orexamples, for implementing different features of the disclosure.Specific examples of components and arrangements are described below tosimplify the present disclosure. These are, of course, merely examplesand are not intended to be limiting. For example, the formation of afirst feature over or on a second feature in the description thatfollows may include embodiments in which the first and second featuresare formed in direct contact, and may also include embodiments in whichadditional features may be formed between the first and second features,such that the first and second features may not be in direct contact. Inaddition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. For example, if the device in the figures is turned over,elements described as being “below” or “beneath” other elements orfeatures would then be oriented “above” the other elements or features.Thus, the exemplary term “below” can encompass both an orientation ofabove and below. The apparatus may be otherwise oriented (rotated 90degrees or at other orientations) and the spatially relative descriptorsused herein may likewise be interpreted accordingly.

The present disclosure relates to the patterning of a workpiece, such asa semiconductor substrate, using lithography. The techniques of thepresent disclosure apply equally to wide range of lithographictechniques, including photolithography and direct-write lithography.Some examples of such a lithographic technique are described withreference to FIGS. 1A-I. FIG. 1A is a flow diagram of a firstlithographic method 100 for patterning a workpiece according to variousaspects of the present disclosure. It is understood that additionalsteps can be provided before, during, and after the method 100 and thatsome of the steps described can be replaced or eliminated for otherembodiments of the method 100. FIGS. 1B-1H are perspective views of aportion of a workpiece 150 undergoing the first lithographic methodaccording to various aspects of the present disclosure. FIG. 1I is a topview of another portion of the workpiece 150 undergoing the firstlithographic method according to various aspects of the presentdisclosure. For clarity and ease of explanation, some elements of thefigures have been simplified.

Referring to block 102 of FIG. 1A and to FIG. 1B, a workpiece 150 isreceived that includes a substrate 152 upon which other materials may beformed. One common type of substrate 152 used in integrated circuit (IC)fabrication is a bulk silicon substrate. Alternatively, the substrate152 may comprise an elementary (single element) semiconductor, such assilicon or germanium in a crystalline structure; a compoundsemiconductor, such as silicon germanium, silicon carbide, galliumarsenic, gallium phosphide, indium phosphide, indium arsenide, and/orindium antimonide; a non-semiconductor material, such as soda-limeglass, fused silica, fused quartz, and/or calcium fluoride (CaF₂);and/or combinations thereof. Possible substrates 152 also include asilicon-on-insulator (SOI) substrate. SOI substrates are fabricatedusing separation by implantation of oxygen (SIMOX), wafer bonding,and/or other suitable methods. In other examples, the substrate 152 mayinclude a multilayer semiconductor structure.

The substrate 152 may include various doped regions (e.g., p-type wellsor n-type wells), such as source/drain regions. The doped regions may bedoped with p-type dopants, such as phosphorus or arsenic, and/or n-typedopants, such as boron or BF₂, depending on design requirements. Thedoped regions may be formed directly on the substrate, in a P-wellstructure, in an N-well structure, in a dual-well structure, or using araised structure. Doped regions may be formed by implantation of dopantatoms, in-situ doped epitaxial growth, and/or other suitable techniques.In some embodiments, the doped regions include halo/pocket regions thatcan reduce short channel effects (e.g., punch-through effects) and maybe formed by tilt-angle ion implantation or other suitable technique.

The substrate 152 may also include various material layers formed uponit. In the illustrated embodiment, the workpiece 150 includes a materiallayer 154 to be patterned and a hard mask layer 156 disposed on thematerial layer 154. Of course, one of skill in the art will recognizethat the substrate 152 may have any number of material layers and/orhard mask layers. Suitable materials for the material layer(s) and hardmask layer(s) may be selected based on etchant selectivity, and invarious exemplary embodiments, material layer 154 and hard mask layer156 have different etchant selectivities such that each layer can beremoved using a corresponding etchant without significant etching of theother layer. For example, various embodiments in which the patterningtechnique is used to pattern an inter-layer dielectric (ILD) in order toform an interconnect structure, material layer 154 includes asemiconductor and/or a dielectric material such as a semiconductoroxide, semiconductor nitride, and/or semiconductor oxynitride; and hardmask layer 156 includes a different material having a different etchantselectivity such as a different semiconductor, dielectric material, ametal nitride (e.g., TiN, TaN, etc.), a metal oxide, a metal oxynitride,and/or a metal carbide.

The substrate 152 may also include a lithographically-sensitive resist158 such as a photoresist and/or e-beam resist tailored to theparticular technique and energy source used in the subsequent patterningsteps. An exemplary resist 158 includes a photosensitive material thatcauses the material to undergo a property change when exposed toradiation. This property change can be used to selectively removeexposed (in the case of a positive tone resist) or unexposed (in thecase of a negative tone resist) portions of the resist layer 158.

Referring to block 104 of FIG. 1A and to FIG. 1C, the resist layer 158is patterned. Patterning may be performed using any suitablelithographic technique including photolithography and/or direct-writelithography. An exemplary photolithographic patterning process includessoft baking of a resist layer, mask aligning, exposure, post-exposurebaking, developing the resist layer, rinsing, and drying (e.g., hardbaking). An exemplary direct-write patterning process includes scanningthe surface of a resist layer with an e-beam or other energy sourcewhile varying the intensity of the energy source in order to vary thedosage received by various regions of the resist layer.

In many conventional patterning techniques, multiple exposures are usedto define a single set of features. For example, a first exposure maydefine large regions corresponding to one or more features, while asecond exposure (often referred to as a line-cut) defines segments ofthe large regions to remove in order to separate the features. However,correctly aligning the exposures in a multiple exposure process ischallenging and alignment errors may render a workpiece unusable.Accordingly, the embodiments of FIGS. 1A-1I provide a technique forseparating features using a line-end shrink process that can separatefeatures without a separate line-cut exposure.

In the example of FIG. 1C, a single recess in the resist layer 158 isused to define two independent, separate, and unconnected features.Feature regions are indicated generally by marker 160. The featureregions 160 within the trench are joined by a line-end linking feature162. A line-end linking feature 162 may be added between any twofeatures and may be used when the features are spaced less than someminimum threshold apart. In the illustrated embodiment, the line-endlinking feature 162 has a narrower width than the feature regions 160.The width is selected so that a spacer material deposited within theline-end linking feature 162 will span the line-end linking feature 162and physically separate the feature regions 160.

Referring to block 106 of FIG. 1A and to FIG. 1D, a spacer 164 is formedon the sidewalls of the remaining resist 158. The spacer 164 may includeany suitable material (e.g., metal oxide, metal nitride, metaloxynitride, metal carbide, semiconductor, dielectric, etc.) and may beselected to have a different etchant selectivity than the hard masklayer 156. The material of the spacer 164 may be deposited by anysuitable process including atomic layer deposition (ALD), chemical vapordeposition (CVD), plasma-enhanced CVD (PE CVD), and/or other suitabledeposition techniques. In one such embodiment, the material of thespacer 164 is deposited conformally by ALD and an anisotropic(directional) etching technique such, as an anisotropic plasma etching,is performed to remove portions of the spacer 164 deposited onhorizontal surfaces of the resist layer 158 and the hard mask layer 156.In this way, only those portions of the spacer 164 deposited on thevertical surfaces of the resist layer 158 remain.

In other embodiments, the material of the spacer 164 is deposited usinga wet chemical reactant selected to react with the resist layer 158 toproduce a precipitate that forms the spacer 164. The workpiece 150 maybe rinsed to remove unreacted reactant and an anisotropic etching may beperformed to remove portions of the spacer 164 deposited on horizontalsurfaces of the resist layer 158 and the hard mask layer 156.

The use of this line-end shrinking technique may provide numerousadvantages. For example, as mentioned above, by using line-end shrinkingand the associated line-end linking features 160, a line-cut process maybe eliminated. In turn, this may avoid complications and defectsassociated with an additional lithographic patterning step. In someapplications, eliminating a line-cut process reduces the number of hardmask layers used to pattern the material layer 154. As another example,because the spacer 164 is formed on the sidewalls of the hard mask layer156, the trench in the hard mask layer 156 formed in block 104 is widerin the line width direction than the feature to be formed. Because manylithographic processes operate at the very limits of the minimumresolvable line width, forming a wider trench in the hard mask layer 156may allow some lithographic rules to be relaxed and may allow theformation of smaller features than would otherwise be possible. Ofcourse, these advantages are merely exemplary, and no advantage isrequired for any particular embodiment.

Referring to block 108 of FIG. 1A and to FIG. 1E, an exposed portion ofthe hard mask layer 156 is etched to transfer the pattern of the resistlayer 158 and the spacer 164 to the hard mask layer 156. The etching mayinclude any suitable etching technique including wet etching, dryetching, reactive ion etching, ashing, and/or other suitable technique,and the etching technique and etchant chemistry may be selected toproduce substantially isotropic etching of the exposed hard mask layer156 without substantial etching of the resist layer 158 and/or spacer164. Referring to FIG. 1F, the resist layer 158 and/or the spacer 164may be removed after etching the hard mask layer 156.

The etched hard mask layer 156 can be used to selectively process anyunderlying portion of the substrate 152 and/or material layers (e.g.,layer 154). In that regard, the hard mask layer 156 may be used inconjunction with any etching process, deposition process, implantationprocess, epitaxy process, and/or any other fabrication process. In someexamples, the material layer 154 is patterned using the hard mask layer156 in order to form an interconnect structure. In one such example,referring to block 110 of FIG. 1A and to FIG. 1G, the exposed portionsof the material layer 154 are patterned using any suitable etchingtechnique including dry etching, wet etching, reactive ion etching,ashing, and/or other suitable etching technique. After the etching, anyremaining portion of the hard mask layer 156 may be removed.

Referring to block 112 of FIG. 1A and to FIG. 1H, one or more layers ofa conductive material 166 are deposited on the patterned material layer154 including within the etched portion. Suitable conductive materials166 include metals, metal oxides, metal nitrides, metal oxynitrides,metal carbides, and/or nonmetallic conductors, and in one suchembodiment, the conductive material 166 includes a TiN barrier layerdisposed on the material layer 154 and a copper-containing fill materialdisposed on the barrier layer. Any portion of the conductive material166 extending above the material layer 154 may be removed using achemical-mechanical polishing/planarization (CMP) process or othersuitable technique.

The technique may also be applied to features of the workpiece 150 thatare offset in the line width direction. Accordingly, FIG. 1I illustratesanother region of the workpiece 150 in which a line-end linking feature162 is used to perform a line-end shrink to separate offset features.FIG. 1I shows the workpiece 150 following the formation of the spacerdescribed in block 106 of FIG. 1A. The method 100 proceeds identically,and in many embodiments, the workpiece 150 includes features that arealigned in the line width direction as shown in FIGS. 1B-1H as well asoffset as shown in FIG. 1I.

Whereas the example of method 100 forms the spacer 164 on the verticalsidewalls of the resist layer 158 and uses the combined spacer 164 andresist layer 158 to pattern the hard mask layer 156, in furtherembodiments, the resist layer 158 is used to pattern the hard mask layer156 and the spacer 164 is subsequently formed on the hard mask layer156. Some embodiments utilizing the later technique are described withreference to FIGS. 2A-I. FIG. 2A is a flow diagram of a secondlithographic method 200 for patterning a workpiece according to variousaspects of the present disclosure. It is understood that additionalsteps can be provided before, during, and after the method 200 and thatsome of the steps described can be replaced or eliminated for otherembodiments of the method 200. FIGS. 2B-2H are perspective views of aportion of a workpiece 150 undergoing the second lithographic methodaccording to various aspects of the present disclosure. FIG. 2I is a topview of another portion of the workpiece 150 undergoing the secondlithographic method according to various aspects of the presentdisclosure. For clarity and ease of explanation, some elements of thefigures have been simplified.

Referring to block 202 of FIG. 2A and to FIG. 2B, a workpiece 150 isreceived that includes a substrate 152 upon which other materials may beformed. In some embodiments, the substrate 152 includes a material layer154, a hard mask layer 156, and a resist layer 158, each substantiallysimilar to those of FIGS. 1A-I. Referring to block 204 of FIG. 2A and toFIG. 2C, the resist layer 158 is patterned. The patterning may beperformed substantially as described with respect to block 104 of FIG.1A and may utilize any suitable lithographic technique includingphotolithography and/or direct-write lithography. In the example of FIG.2C, a single recess in the resist layer 158 is used to define twoindependent, separate, and unconnected features. Feature regions areindicated generally by marker 160. The feature regions 160 within thetrench are joined by a line-end linking feature 162. A line-end linkingfeature 162 may be added between any two features and may be used whenthe features are spaced less than some minimum threshold apart. In theillustrated embodiment, the line-end linking feature 162 has a narrowerwidth than the feature regions 160. The width is selected so that aspacer material deposited within the line-end linking feature 162 willspan the line-end linking feature 162 and physically separate thefeature regions 160.

Referring to block 206 of FIG. 2A and to FIG. 2D, the patterned resist158 is used to selectively remove a portion of the hard mask layer 156.This transfers the pattern of the resist 158 to the hard mask layer 156.The etching may include any suitable etching technique including wetetching, dry etching, reactive ion etching, ashing, and/or othersuitable technique, and the etching technique and etchant chemistry maybe selected to produce substantially isotropic etching of the exposedhard mask layer 156 without substantial etching of the resist layer 158.Referring to FIG. 2E, the remaining resist layer 158 may be removedafter etching the hard mask layer 156.

Referring to block 208 of FIG. 2A and to FIG. 2F, a spacer 164 is formedon the sidewalls of the remaining hard mask layer 156. The spacer 164may be substantially similar to that of FIGS. 1A-1I and may include anysuitable material (e.g., metal oxide, metal nitride, metal oxynitride,metal carbide, semiconductor, dielectric, etc.). The material of thespacer 164 may be selected to have a different etchant selectivity thanthe material layer 154. The material of the spacer 164 may be depositedby any suitable process including atomic layer deposition (ALD),chemical vapor deposition (CVD), plasma-enhanced CVD (PE CVD), and/orother suitable deposition techniques. In one such embodiment, thematerial of the spacer 164 is deposited conformally by ALD and ananisotropic (directional) etching technique such, as an anisotropicplasma etching, is performed to remove portions of the spacer 164deposited on horizontal surfaces of the hard mask layer 156 and thematerial layer 154. In this way, only those portions of the spacer 164deposited on the vertical surfaces of the hard mask layer 156 remain.

In other embodiments, the material of the spacer 164 is deposited usinga wet chemical reactant selected to react with the hard mask layer 156to produce a precipitate that forms the spacer 164. The workpiece 150may be rinsed to remove unreacted reactant and an anisotropic etchingmay be performed to remove portions of the spacer 164 deposited onhorizontal surfaces of the hard mask layer 156 and the material layer154.

The spacer 164 and the hard mask layer 156 can be used to selectivelyprocess any underlying portion of the substrate 152 and/or materiallayers (e.g., layer 154). In that regard, the spacer 164 and the hardmask layer 156 may be used in conjunction with any etching process,deposition process, implantation process, epitaxy process, and/or anyother fabrication process. In some examples, the material layer 154 ispatterned using the spacer 164 and the hard mask layer 156 in order toform an interconnect structure. In one such example, referring to block210 of FIG. 2A and to FIG. 2G, the exposed portions of the materiallayer 154 are patterned using any suitable etching technique includingdry etching, wet etching, reactive ion etching, ashing, and/or othersuitable etching technique. After the etching, any remaining portion ofthe spacer 164 and/or hard mask layer 156 may be removed.

Referring to block 212 of FIG. 2A and to FIG. 2H, one or more layers ofa conductive material 164 are deposited on the patterned material layer154 including within the etched portion. Suitable conductive materials164 include metals, metal oxides, metal nitrides, metal oxynitrides,metal carbides, and/or nonmetallic conductors, and in one suchembodiment, the conductive material 164 includes a TiN barrier layerdisposed on the material layer 154 and a copper-containing fill materialdisposed on the barrier layer. Any portion of the conductive material164 extending above the material layer 154 may be removed using achemical-mechanical polishing/planarization (CMP) process or othersuitable technique.

The technique may also be applied to features of the workpiece 150 thatare offset in the line width direction. Accordingly, FIG. 2I illustratesanother region of the workpiece 150 in which a line-end linking feature162 is used to perform a line-end shrink to separate offset features.FIG. 2I shows the workpiece 150 following the formation of the spacerdescribed in block 208 of FIG. 2A. The method 200 proceeds identically,and in many embodiments, the workpiece 150 includes features that arealigned in the line width direction as shown in FIGS. 2B-2H as well asoffset as shown in FIG. 2I.

Further embodiments of the lithographic patterning technique will now bedescribed with reference to FIGS. 3-17. FIG. 3 is a flow diagram of amethod 300 for patterning a workpiece 500 according to various aspectsof the present disclosure. It is understood that additional steps can beprovided before, during, and after the method 300 and that some of thesteps described can be replaced or eliminated for other embodiments ofthe method 300. FIG. 4 is a representation of a design database 400specifying a pattern to be formed on the workpiece according to variousaspects of the present disclosure. FIGS. 5A, 6A, 7A, 8A, 9A, 10A, 11A,12A, 13A, 14A, 15A, and 16A are top views of a portion of the workpiece500 undergoing the patterning method according to various aspects of thepresent disclosure. FIGS. 5B, 6B, 7B, 8B, 9B, 10B, 11B, 12B, 13B, 14B,15B, and 16B are corresponding cross-sectional views of a portion of theworkpiece undergoing the patterning method according to various aspectsof the present disclosure. The cross-sectional plane is shown in FIG. 5Aby reference line 501. FIG. 17 is a scanning-electron microscope (SEM)image 1700 of a workpiece 500 having undergone the patterning methodaccording to various aspects of the present disclosure. For clarity andease of explanation, some elements of the figures have been simplified.

Referring to block 302 of FIG. 3 and to FIG. 4, a design database 400 isreceived at a computing system. The design database 400 includes anynumber of features 402 to be formed on the workpiece and representsthese features in the form of a data file stored on a non-transitorycomputer-readable medium. Various design standards exist forrepresenting the features 402 including GDSII, OASIS, CIF (CaltechIntermediate Form), and MEBES®, a registered trademark of AppliedMaterials, and in various embodiments, the design database 400represents the features 402 in these and/or other suitable formats. Inthe illustrated embodiment, the features 402 are aligned in tracks 404.Tracks are typically used to align features 402 according to a minimumspacing although there is no requirement that a feature 402 be alignedwith a track 404.

Referring to block 304 of FIG. 3 and to FIG. 4, the features 402 aregrouped based in part on the tracks 404 to which they are aligned. Inthe illustrated embodiment of FIG. 4, the tracks 404 correspond to threegroups, labeled A, B, and C, according to a repeating pattern. In thisexample, features 402 in group A have a first pitch (e.g., acenter-to-center spacing interval) with respect to the other features402 in the group, and features 402 in group B have a similar pitch withrespect to the other features 402 in the group. However, in thisexample, features in group C have a smaller pitch, in part because groupC is associated with every other track 404. To support this smallerpitch, design rules may be implemented to ensure the fidelity offeatures 402 in group C. For example, a design rule may requireminimum-spaced group C features to be separated by either a group Bfeature or a group A feature. In another example, a design rule mayprohibit line ends of group B features or group A features to occurbetween minimum-spaced group C features. These design rules and othersmay place undesirable constraints on the design database 400.Accordingly, the technique of method 300 provides a multiple patterningtechnique free from some or all of these design rules. This givesdesigners greater leeway, which may be leveraged to simplify routing andto form more features 402 in a smaller area.

Referring to block 306 of FIG. 3, the design database 400 including thegrouped features is provided for lithographic preparation. In one suchexample, a mask house or other entity performs optical proximitycorrection (OPC) on the design database 400 by adding sub-resolutionassist features, serifs, hammerheads, and/or other enhancements to thedatabase features 402. Other types of optical compensation are describedin more detail below. Some lithographic preparation steps performed inblock 306 are specific to the type of lithographic technique to beperformed. For example, for a direct-write lithographic technique,preparation may include generating a set of emitter intensity valuesand/or other beam controls for an emitter (e.g., a laser, an e-beamemitter, an ion beam emitter, etc.) based on the features 402 of thedesign database 400.

For a photolithographic technique, preparation may include generatingone or more masks (e.g., reflective and/or transmissive masks) based onthe design database 400. In one such example, a mask house uses thedesign database 400 to manufacture a mask or mask set. In some suchembodiments, an e-beam or e-beam array is used to pattern a mask byexposing portions of a beam resist formed on the mask. The patternedresist is then used to remove regions of an optical layer such as anabsorptive layer of the mask. Additionally or in the alternative, thee-beam removes the optical layer directly by ablation or adds to theoptical layer by performing a pinpoint deposition. Direct ablation anddeposition are often used to correct mask defects. In that regard, aftera mask has been fabricated, the mask house performs a mask inspection todetermine if the fabricated mask includes any defects. Depending on thenumber and type of defects present, the mask may be repaired orrecycled.

Referring to blocks 308-324, the result of this preparation, whether itis a mask set, direct-write instructions, or other lithographicrepresentation, is used to pattern one or more material layers of aworkpiece. FIGS. 5A and 5B show one such suitable workpiece 500. Theexemplary workpiece includes a substrate 502 upon which other materialsmay be formed. The substrate 502 may be substantially similar tosubstrate 152 of FIGS. 1A-1I and/or 2A-2I and may include an elementarysemiconductor, a compound semiconductor, a non-semiconductor material,and/or a combination thereof.

The substrate 502 may also include various material layers formed uponit. In the illustrated embodiment, the workpiece 500 includes a materiallayer 504 to be patterned and two hard mask layers (layer 506 and layer508) disposed on the material layer. These may be substantially similarto those described in the context of FIGS. 1A-1I and/or 2A-2I. Ofcourse, one of skill in the art will recognize that the substrate 502may have any number of material layers and/or hard mask layers. Suitablematerials for the material layers and hard mask layers may be selectedbased on etchant selectivity, and in various exemplary embodiments,material layer 504, hard mask layer 506, and hard mask layer 508 havedifferent etchant selectivities such that each layer can be removedusing a corresponding etchant without significant etching of the otherlayers. For example, various embodiments in which the patterningtechnique is used to pattern an inter-layer dielectric (ILD) in order toform an interconnect structure, material layer 504 includes asemiconductor and/or a dielectric material such as a semiconductoroxide, semiconductor nitride, and/or semiconductor oxynitride; hard masklayer 506 includes a different material having a different etchantselectivity such as a metal nitride (e.g., TiN, TaN, etc.), metal oxide,metal oxynitride, metal carbide, semiconductor, and/or dielectric; andhard mask layer 508 includes yet another material such as a differentmetal nitride, metal oxide, metal oxynitride, metal carbide,semiconductor, and/or dielectric. In one such embodiment, material layer504 includes silicon oxynitride, hard mask layer 506 includes titaniumnitride, and hard mask layer 508 includes amorphous silicon.

Workpiece 500 may also include a lithographically-sensitive resist 510such as a photoresist and/or e-beam resist tailored to the particulartechnique and energy source used in the subsequent patterning steps. Anexemplary resist 510 includes a photosensitive material that causes thematerial to undergo a property change when exposed to radiation. Thisproperty change can be used to selectively remove exposed (in the caseof a positive tone resist) or unexposed (in the case of a negative toneresist) portions of the resist layer 510.

Referring to block 308 and to FIGS. 6A and 6B, a first patterning of theworkpiece 500 is performed to form a first pattern in the resist layer510. Patterning may be performed using any suitable lithographictechnique including photolithography and/or direct-write lithography. Anexemplary photolithographic patterning process includes soft baking ofthe resist layer 510, mask aligning, exposure, post-exposure baking,developing the resist layer 510, rinsing, and drying (e.g., hardbaking). An exemplary direct-write patterning process includes scanningthe surface of the resist layer 510 with an e-beam or other energysource while varying the intensity of the energy source in order to varythe dosage received by various regions of the resist layer 510. Thepattern formed in the resist layer 510 by the first patterning of theworkpiece 500 is based on the design database 400, and in particular onfeatures 402 in group A. Specifically, in the illustrated embodiment,the patterned resist layer 510 covers each group B track, exposes eachgroup C track that is not adjacent to a line-end linking feature 608(explained in more detail below), and exposes those group A tracks inwhich a feature 402 is to be formed. Referring to FIG. 6A, tracks 404have been superimposed on the workpiece 500 to mark the relativelocations of these feature groups. In the illustrated embodiment, theedges of the pattern shape are located so that a spacer subsequentlyformed on the patterned hard mask layer 508 extends along those portionsof the group C tracks that are not adjacent to a line-end linkingfeature 608. This becomes more evident in subsequent figures.

As can be seen, the pattern formed on the workpiece 500 is related tothe features 402 of the design database 400 but also includesmodifications made to the design database 400 in block 306. To furtherillustrate this point, two group A features to be formed are representedby dotted boxes 602. In the illustrated embodiment, the correspondingpatterned area of the resist 510 is larger in a direction parallel tothe respective track 404 and in a direction perpendicular to therespective track 404 as indicated by reference markers 604 and 606,respectively. The patterned area of the resist 510 also includes aline-end linking feature represented by dotted box 608. The line-endlinking features 608 may be substantially similar to line-end linkingfeatures 162 of FIGS. 1A-1I and/or 2A-2I, and in that regard, line-endlinking features 608 may be added between any two group A featuresspaced less than some minimum threshold apart. In the illustratedembodiment, the line-end linking feature region has a narrower widthperpendicular to the track 404 than the feature region. These opticalcorrections (expanded feature area and line-end linking features 608)and others may be made to the design database 400 during the processingof block 306 or may be made to a mask or a set of direct-writeinstructions without updating the design database 400.

Referring to block 310 of FIG. 3 and to FIGS. 7A and 7B, the pattern ofthe resist 510 is transferred to the remainder of the workpiece 500 byany suitable etching process including wet etching, dry etching,reactive ion etching, ashing, and/or other suitable technique. Theetching process and/or etching reagents may be selected to etch hardmask layer 508 without significant etching of hard mask layer 506. Anyremaining resist 510 may be stripped following the patterning of hardmask layer 508.

Referring to block 312 of FIG. 3 and to FIGS. 8A and 8B, a first spacer802 is formed on the sidewalls of the remaining hard mask layer 508. Thefirst spacer 802 may include any suitable material (e.g., metal oxide,metal nitride, metal oxynitride, metal carbide, semiconductor,dielectric, etc.), which may be selected to have a different etchantselectivity than the surrounding layers (e.g., hard mask layer 508, hardmask layer 506, etc.). In an exemplary embodiment, the first spacer 802includes TiO in order to differentiate it from an amorphous silicon hardmask layer 508 and a TiN-containing hard mask layer 506.

The material of the first spacer 802 may be deposited by any suitableprocess including atomic layer deposition (ALD), chemical vapordeposition (CVD), plasma-enhanced CVD (PE CVD), and/or other suitabledeposition techniques. In one such embodiment, the material of the firstspacer 802 is deposited conformally by ALD and an anisotropic(directional) etching technique such, as an anisotropic plasma etching,is performed to remove portions of the first spacer 802 deposited onhorizontal surfaces of hard mask layer 508 and hard mask layer 506. Inthis way, only those portions of the first spacer 802 deposited on thevertical surfaces of hard mask layer 508 remain.

In other embodiments, the material of the first spacer 802 is depositedusing a wet chemical reactant selected to react with hard mask layer 508to produce a precipitate that forms the first spacer 802. The workpiece500 may be rinsed to remove unreacted reactant and an anisotropicetching may be performed to remove portions of the first spacer 802deposited on horizontal surfaces of hard mask layer 508 and hard masklayer 506.

Referring to block 314 of FIG. 3 and to FIGS. 9A and 9B, a second resist902 (e.g., a photoresist, e-beam resist, etc.) is formed on theworkpiece 500 and patterned to form a second pattern. The patterning maybe performed by any suitable technique including photolithography and/ordirect-write lithography and may be of a different type than thetechnique used to pattern the first resist layer 510. The pattern formedin the second resist layer 902 is based on the design database 400, andin particular on features 402 in group B. In the illustrated embodiment,the patterned resist layer 902 covers each group A track, exposes eachgroup C track, and exposes those portions of group B tracks in which afeature 402 is to be formed.

Referring to block 316 of FIG. 3 and to FIGS. 10A and 10B, the patternof the second resist 902 is transferred to the workpiece 500 by removingthose portions of the hard mask layer 508 exposed by the second resist902. The transfer may be achieved using any suitable etching processincluding wet etching, dry etching, reactive ion etching, ashing, and/orother suitable technique. The etching process and/or etching reagentsmay be selected to etch hard mask layer 508 without significant etchingof hard mask layer 506 and/or the first spacer 802. Any remaining secondresist 902 material may be stripped following the patterning of hardmask layer 508.

Referring to block 318 of FIG. 3 and to FIGS. 11A and 11B, a secondspacer 1102 is formed on the sidewalls of the first spacer 802 and/orany remaining portion of hard mask layer 508. The second spacer 1102 mayinclude any suitable material (e.g., metal oxide, metal nitride, metaloxynitride, metal carbide, semiconductor, dielectric, etc.), which maybe selected to have a different etchant selectivity than the surroundinglayers (e.g., hard mask layer 508, hard mask layer 506, first spacer802, etc.). In an exemplary embodiment, the second spacer 1102 includessilicon dioxide in order to differentiate it from a TiO-containing firstspacer 802, an amorphous silicon hard mask layer 508, and aTiN-containing hard mask layer 506.

Similar to the first spacer 802, the material of the second spacer 1102may be deposited by any suitable process including atomic layerdeposition (ALD), chemical vapor deposition (CVD), plasma-enhanced CVD(PE CVD), and/or other suitable deposition techniques. In one suchembodiment, the material of the second spacer 1102 is depositedconformally by ALD and subsequently etched using an anisotropic(directional) etching technique to remove portions of the second spacer1102 deposited on horizontal surfaces of hard mask layer 508, hard masklayer 506, and/or the first spacer 802. In this way, only those portionsof the second spacer 1102 deposited on the vertical surfaces of thefirst spacer 802 and/or hard mask layer 508 remain.

In other embodiments, the material of the second spacer 1102 isdeposited using a wet chemical reactant selected to react with thematerials of the workpiece 500 to produce a precipitate that forms thesecond spacer 1102. The workpiece 500 may be rinsed to remove unreactedreactant and an anisotropic etching may be performed to remove portionsof the second spacer 1102 deposited on horizontal surfaces of hard masklayer 508, hard mask layer 506, and/or the first spacer 802.

Referring to block 320 of FIG. 3 and to FIGS. 12A and 12B, a thirdresist 1202 (e.g., a photoresist, e-beam resist, etc.) is formed on theworkpiece 500 and patterned to form a third pattern. The patterning maybe performed by any suitable technique including photolithography and/ordirect-write lithography and may be of a different type than thetechnique used to pattern the first resist layer 510 and the secondresist layer 902. The pattern formed in the third resist 1202 is basedon the design database 400, and in particular on features 402 in groupC. In the illustrated embodiment, the patterned resist layer 1202exposes those portions of group C tracks in which a feature 402 is to beformed.

Referring to block 322 of FIG. 3 and to FIGS. 13A and 13B, the patternof the third resist 1202 is transferred to the workpiece 500 by removingthose portions of the first spacer 802 exposed by the third resist 1202.The transfer may be achieved using any suitable etching processincluding wet etching, dry etching, reactive ion etching, ashing, and/orother suitable technique. The etching process and/or etching reagentsmay be selected to etch the first spacer 802 without significant etchingof the surrounding material layers including the second spacer 1102. Anyremaining resist 1202 may be stripped following the patterning. At thispoint, the finished pattern has been defined by the remainder of thehard mask layer 508, first spacer 802, and/or second spacer 1102. Theworkpiece can be selectively processed using this pattern without anyfurther patterning. However, in some embodiments, as part of thisprocessing, the pattern is first transferred to another hard mask layer(e.g., hard mask layer 506).

Accordingly, referring to block 324 of FIG. 3 and to FIGS. 14A and 14B,hard mask layer 506 is patterned using any remaining portions of hardmask layer 508, first spacer 802, and/or second spacer 1102. Thispatterning may be achieved using any suitable etching process includingwet etching, dry etching, reactive ion etching, ashing, and/or othersuitable technique. Following the patterning of the hard mask layer 506,the remaining portions of the hard mask layer 508, the first spacer 802,and/or the second spacer 1102 may be removed.

As can be seen from the preceding description, this patterning techniquepossesses several advantages not found in other multiple patterningtechniques. For example, the line-end linking feature 608 (shown in FIG.6A) allows for precise control of line-end spacing without a separateline-cut patterning step. Avoiding a line-cut patterning step may reducethe number of hard mask layers and may avoid the mask cost and timeassociated with the extra patterning step. Additionally, in someembodiments, this technique allows line-ends to be formed in the regionswhere they are not permitted in other techniques (e.g., betweenminimum-spaced group C features). Of course, these advantages are merelyexemplary, and no advantage is required for any particular embodiment.

Using the technique of blocks 302-324, a pattern is formed in the hardmask layer 506 based on the three iterations of lithographic patterningin order to form a pattern specified in the design database 400. Thehard mask layer 506 can then be used to selectively process theunderlying substrate 502 and/or material layers (e.g., layer 504). Thepatterned hard mask layer 506 may be used in conjunction with anyetching process, deposition process, implantation process, epitaxyprocess, and/or any other fabrication process. In some examples,described in the context of block 326 of FIG. 3 and FIGS. 15A and 15B, amaterial layer 504 is patterned using the hard mask layer 506 in orderto form an interconnect structure. In so doing, the exposed portions ofthe material layer 504 are patterned using any suitable etchingtechnique including dry etching, wet etching, reactive ion etching,ashing, and/or other suitable etching technique. After the etching, anyremaining portion of the hard mask layer 506 may be removed.

Referring to block 328 and to FIGS. 16A and 16B, one or more layers of aconductive material 1602 are deposited on the patterned material layer504 including within the etched portion. Suitable conductive materials1602 include metals, metal oxides, metal nitrides, metal oxynitrides,metal carbides, and/or nonmetallic conductors, and in one suchembodiment, the conductive material 1602 includes a TiN barrier layerdisposed on the material layer 504 and a copper-containing fill materialdisposed on the barrier layer. Any portion of the conductive material1602 extending above the material layer 504 may be removed using achemical-mechanical polishing/planarization (CMP) process or othersuitable technique.

FIG. 17 is an annotated scanning-electron microscope (SEM) image of aworkpiece 500 having undergone the patterning method according tovarious aspects of the present disclosure. In the illustratedembodiments, there are some nonlinear feature portions, particularly ingroups B and C, examples of which are indicated by reference markers1702 and 1704. However, in many applications this non-linearity hasminimal electrical and/or performance impact on the finished workpiece500 and is an acceptable tradeoff for the benefits provided by thepresent technique such as the ability to form line-ends betweenminimally-spaced group C features without the burden of extra patterningsteps.

FIG. 18 is a system diagram of a computing system 1800 operable toperform the techniques of the present disclosure. The computing system1800 may include a processor 1802 such as a microcontroller or adedicated central processing unit (CPU), a non-transitorycomputer-readable storage medium 1804 (e.g., a hard drive, random accessmemory (RAM), a compact disk read only memory (CD-ROM), etc.), a videocontroller 1806 such as a graphics processing unit (GPU), and a networkcommunication device 1808 such as an Ethernet controller or wirelesscommunication controller. In that regard, in some embodiments, thecomputing system 1800 is programmable and is programmed to executeprocesses including those associated with grouping features, preparing adesign database 400 for lithography, and patterning a workpiece 500based on the design database 400. Accordingly, it is understood that anyoperation of the computing system 1800 according to the aspects of thepresent disclosure may be implemented by the computing system 1800 usingcorresponding instructions stored on or in a non-transitory computerreadable medium accessible by the processing system. In that regard, thecomputing system 1800 is operable to perform one or more of the tasksdescribed with respect to FIGS. 1A, 2A, and/or 3.

The present embodiments can take the form of an entirely hardwareembodiment, an entirely software embodiment, or an embodiment containingboth hardware and software elements. Furthermore, embodiments of thepresent disclosure can take the form of a computer program productaccessible from a tangible computer-usable or computer-readable mediumproviding program code for use by or in connection with a computer orany instruction execution system. For the purposes of this description,a tangible computer-usable or computer-readable medium can be anyapparatus that can store the program for use by or in connection withthe instruction execution system, apparatus, or device. The medium mayinclude non-volatile memory including magnetic storage, solid-statestorage, optical storage, cache memory, Random Access Memory (RAM).

Thus, the present disclosure provides a technique for forming featureson a workpiece that offers greater design flexibility and fewer designrestrictions. In some embodiments, the provided method includesreceiving a workpiece including a material layer and a hard maskmaterial disposed thereupon. A lithographic patterning of the hard maskmaterial is performed to define a recess therein. A spacer material isdeposited within the recess of the patterned hard mask material todefine at least two physically separated feature regions, and a portionof the workpiece is selectively processed based on a pattern defined bythe patterned hard mask material and the spacer material within therecess. In some such embodiments, the depositing of the spacer materialwithin the recess includes performing a substantially conformaldeposition of the spacer material and performing an etching processconfigured to leave a portion of the spacer material on a side surfaceof the hard mask layer. In some such embodiments, the processing of theportion of the workpiece includes etching an exposed portion of thematerial layer based on the pattern and depositing a conductive materialwithin the etched material layer.

In further embodiments, the provided method includes receiving a datasetspecifying a plurality features to be formed on the workpiece. A firstpatterning of a hard mask of the workpiece is performed based on a firstset of features of the plurality of features; and thereafter, a firstspacer material is deposited on a sidewall of the patterned hard mask. Asecond patterning of the hard mask is performed based on a second set offeatures of the plurality of features; and thereafter, a second spacermaterial is deposited on a sidewall of the first spacer material. Athird patterning of the workpiece is performed based on a third set offeatures of the plurality of features. A portion of the workpiece isselectively processed using a pattern defined by a remainder of at leastone of the patterned hard mask layer, the first spacer material, or thesecond spacer material, the remainder remaining after the performing ofthe first patterning, the second patterning, and the third patterning.In one such embodiment, the performing of the first patterning includesforming a linking feature between a first feature region of the firstset of features and a second feature region of the first set offeatures. The linking feature may have a width less than each of thefirst feature region and the second feature region.

In further embodiments, a method of patterning a material layer isprovided. The method includes receiving a workpiece including thematerial layer and a hard mask layer. The hard mask layer is patternedaccording to a first set of features to be formed on the workpiece. Afirst spacing material is deposited on a side surface of the patternedhard mask layer, and thereafter the hard mask layer is patternedaccording to a second set of features to be formed on the workpiece. Asecond spacing material is deposited on at least one side surface of atleast one of: the hard mask layer or the first spacing material.Thereafter, the first spacing material is patterned according to a thirdset of features to be formed on the workpiece. A pattern is transferredto the material layer, the pattern being defined by at least one of: thehard mask layer, the first spacing layer; or the second spacing layer.In some such embodiments, the patterning of the first spacing materialis configured to avoid significant etching of an exposed portion of thesecond spacing material. In some such embodiments, the patterning of thehard mask layer according to the first set of features includes forminga linking feature between a first feature and a second feature, each ofthe first set of features.

In yet further embodiments, a method of semiconductor fabrication isprovided that includes receiving a substrate having a material layerdisposed thereupon and having a hard mask layer disposed on the materiallayer. A set of features to be formed in the material layer isidentified. The features of the set of features are grouped according totracks with which the features are aligned. The hard mask layer ispatterned according to a first group of features of the set of features,and thereafter a first spacer material is deposited within the hard masklayer. The hard mask layer having the first spacer material depositedtherein is patterned according to a second group of features of the setof features. A second spacer material is deposited that is differentfrom the first spacer material within the hard mask layer. The firstspacer material is patterned according to a third group of features ofthe set of features, and the material layer is patterned based on apattern defined by at least one of: the hard mask layer, the firstspacer material, or the second spacer material.

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions, andalterations herein without departing from the spirit and scope of thepresent disclosure.

What is claimed is:
 1. A method comprising: receiving a workpieceincluding a material layer and a hard mask material disposed thereupon;performing a lithographic patterning of the hard mask material to definea recess therein, wherein the patterned hard mask material furtherdefines a linking feature; depositing a spacer within the recess of thepatterned hard mask material to define at least two physically separatedfeature regions within the recess, wherein the linking feature isdisposed between the at least two physically separated feature regions;and selectively processing a portion of the workpiece based on a patterndefined by the patterned hard mask material and the spacer within therecess.
 2. The method of claim 1, wherein the depositing of the spacerwithin the recess includes performing a substantially conformaldeposition of the spacer and performing an etching process configured toleave a portion of the spacer on a side surface of the hard maskmaterial.
 3. The method of claim 2, wherein the substantially conformaldeposition includes an atomic layer deposition (ALD) process.
 4. Themethod of claim 2, wherein the substantially conformal depositionincludes exposing the hard mask material to a liquid reactant to depositthe spacer.
 5. The method of claim 1, wherein the processing of theportion of the workpiece includes etching an exposed portion of thematerial layer based on the pattern.
 6. The method of claim 5, whereinthe processing of the portion of the workpiece further includesdepositing a conductive material within the etched material layer.
 7. Amethod of patterning a workpiece, the method comprising: receiving adataset specifying a plurality features to be formed on the workpiece;performing a first patterning of a hard mask of the workpiece based on afirst set of features of the plurality of features, wherein the firstpatterning defines at least an individual recess within the hard mask;thereafter depositing a first spacer material on a sidewall of thepatterned hard mask within the individual recess; performing a secondpatterning of the hard mask based on a second set of features of theplurality of features; thereafter depositing a second spacer material ona sidewall of the first spacer material within the individual recess, todefine at least two physically separated feature regions within theindividual recess; performing a third patterning of the workpiece basedon a third set of features of the plurality of features; and selectivelyprocessing a portion of the workpiece using a pattern defined by aremainder of at least one of the hard mask layer, the first spacermaterial, or the second spacer material, the remainder remaining afterthe performing of the first patterning, the second patterning, and thethird patterning.
 8. The method of claim 7, wherein the performing ofthe third patterning includes selectively removing an exposed portion ofthe first spacer material.
 9. The method of claim 7, wherein theperforming of the third patterning is configured to avoid significantetching of an exposed portion of the second spacer material.
 10. Themethod of claim 7, wherein the performing of the first patterningincludes forming a linking feature between a first feature region of thefirst set of features and a second feature region of the first set offeatures, and wherein the linking feature has a width less than each ofthe first feature region and the second feature region.
 11. The methodof claim 7, wherein the performing of the first patterning is configuredsuch that the depositing of the first spacer material deposits the firstspacer material within a region corresponding to the third set offeatures.
 12. The method of claim 11, wherein the performing of thefirst patterning is configured such that the depositing of the firstspacer material deposits the first spacer material within each trackcorresponding to the third set of features that is not adjacent afeature linking two features of the first set of features.
 13. Themethod of claim 7, wherein the third set of features have a track pitchwithin the set that is different from a track pitch within the first setof features and a track pitch within the second set of features.
 14. Themethod of claim 13, wherein the track pitch within the third set offeatures is about half as large as the track pitch within the first setand the track pitch within the second set.
 15. The method of claim 7,wherein the processing of the portion of the workpiece includespatterning another hard mask layer that is different from the patternedhard mask layer based on the pattern defined by the remainder.
 16. Amethod of patterning a material layer, the method comprising: receivinga workpiece including the material layer and a hard mask layer;patterning the hard mask layer according to a first set of features tobe formed on the workpiece, wherein the patterning defines a recess inthe hard mask layer; depositing a first spacing material on a sidesurface of the patterned hard mask layer within the recess; thereafterpatterning the hard mask layer according to a second set of features tobe formed on the workpiece; depositing a second spacing material on atleast one side surface of the first spacing material within theindividual recess, to define at least two physically separated featureregions within the recess; thereafter patterning the first spacingmaterial according to a third set of features to be formed on theworkpiece; and transferring to the material layer a pattern defined byat least one of: the hard mask layer, the first spacing layer; or thesecond spacing layer.
 17. The method of claim 16, wherein the patterningof the first spacing material is configured to avoid significant etchingof an exposed portion of the second spacing material.
 18. The method ofclaim 16, wherein the patterning of the hard mask layer according to thefirst set of features includes forming a linking feature between a firstfeature and a second feature, each of the first set of features.
 19. Themethod of claim 18, wherein the linking feature has a width that is lessthan a width of a region associated with the first feature and less thana width of a region associated with the second feature.
 20. The methodof claim 16, wherein the patterning of the hard mask layer according tothe first set of features is configured such that the depositing of thefirst spacing material deposits the first spacing material within aregion corresponding to the third set of features.